Selective time-limit controlling device for electric switches.



G. A. BURNHAM. SELECTIVE TIME LIMIT CONTROLLING DEVICE FOR ELECTRIC SWITCHES. APPLICATION FILED IULY 2a. 1911.

1 ,288,500, Patented Dec. 24, 1918.

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G. A. BURNHAM.

SELECTIVE TIME LIMIT CONTROLLING DEVICE FOR ELECTRIC SWITCHES. APPLICATION FILED JULY 2a. 191:.

'1 ,288,500. Patented Dec. 24, 1918. I

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- silence A. teniannaan To all whom it may concern:

snnnc'rrvn TIME-LIMIT oon'reonr'anc n n'vrcnroa nnnoraro swmcnns.

Be it known that l, GEORGE A. BURNHAM, a citizen of the United States, residing a Saugus, in the county of Essex and State of Massachusetts, have invented an Improvement in Selective Time-Limit Controlling Devices for Electric Switches, of which the following is a specification.

This invention relates to time-limit con trolling-devices for electric-switches. Heretofore time-limit controlling-devices for electric-switches have been devised including operating-means for the switch, and a retard-. ing-device to regulate the speed of motion of the time-controlled or movable element of said operatinganeans, whereby a prolonged period of time is consumed in operating the switch, and said retarding-device has-been made manually adjustable so that the period of time consumed by the operating-means in operating the switch may be regulated, andmeans responsive to an overload. has been employed for destroying the effective resistance of the retarding-device, so that the operation of the switch is substantially instantaneous. In order that tin1e-limit controlling-devices shall be edective on different overloads, and particularly when it is desired that they shall be selective in action, it is necessary that the prolonged period of time 4 required for the operating-means to operate the switch shall be variably adjusted by means controlled by the overload current, in-

order that it may be reduced more or less according to the strength of the overload.

This invention has for its object the construction of a time-limit controlling-device for electric-switches including operatingmeans for the switch and a retarding-device, whereby a prolonged period of time is required for the operating-means to operate the switch, and means, controlled by an overload current, to vary the length of said period of time, whereby it may be substantially reduced on a heavy overload, the reduction varying according to the strength of the overload; as for instance, said retarding-device may be regulated or controlled by the overload current, in such manner that the resistance offered by it is variable according to the strength of the overload, such adjust ment permitting said retarding-device to otter less resistance on a heavy overload than on a light overload, so that the operatingmeans will be more quickly caused to operate Specification of Letters Patent.

Patented- Dec. 24, 1918.

the switch upon a heavy overload than upon a light overload, yet in any event a period of time of substantial duration is maintained.

The movable element of the operatingmeans may be arranged lO-I'BCGlVG a uniform thrust regardless of the strength of the overload, or a thrustwhich varies according to the strength of the overload, actuators designed to exert a uniform and also a variable thrust being here shown for illustration.

Figure 1 is a sectional view of a time-limit controlling-device for electric-switches embodying this invention.

Fig. 2 is a sectional detail view of the controlling-valve for the dash-pot.

Fig. 3 is a sectional view of a modified form of time-limit controlling-device to be referred to.

Referring to Figs. 1 and 2 wherein a single line-circuit is shown as a simple manner of illustrating my invention, 20 represents the circuit or line-wire, and 21, a switch of any suitable construction, but preferably of atype adapted to be operated automatically to open the circuit, and manually to close the same. A snap-switch of usual construction is here shown, having a hand-lever 22, and an actuating-spring 23. This is the switch which the time-limit controlling-device forming the subject-matter of this application is designed to operate automatically, to open the circuit 20. i

The time-limit controlling-device of Fig. 1, involves operating-means for the switch, and means responsive to an overload current to actuate it or to control its operation, also a retarding-device, and means responsive to the overload current to ad ust sald retardingdevice, whereby the period of tlme required for the operating-means to operate the switch is reduced according to the strength of the overload.

As here shown for the purpose of illustrating my invention said operating-means comprises a switch-controller of the electrical type, which is adapted, when operated, to open the switch, and an operating-device for the circuit of said switch-controller which requires a. prolonged period of time to complete its operation and operate the switch-controll er.

The switch-controller here shown consists of a solenoid 2 L, connected in a battery circuit 25, the armature of which is designed to engage and operate'a snap-switch to open the circuit 20, upon energization of the solenoid.

The operating-device for the switch-controller, as here shown, consists of circuit controlling-devices for the circuit 25, and a movis movable, as hereinafter described to cause the circuit-contacts borne by it to engage the stationary circuit-contacts and close the circuit 25, and thereby operate the switch to open the circuit 20. As an actuator for the movable element bearing the circuit-contacts 27 a magnet or solenoid-coil is here shown, which is included in a circuit 36, of a transformer, of which 37 is the secondarycoil, and 38 the primary-coil, and said primary-coil is included in the circuit 20, which is being controlled, so that the solenoid 35 is under the control 'of or responsive to an 'of a dash-pot through a helical spring 45,-

overload on thecircuit 20. Said solenoid may be of any well known or suitable con-J 'structlon, but herein the coil is provided with a brass tubular lining within which is gulded a soft iron core 40. Said core is adjustably arranged within a tubular carrier 41, to permit regulation of.the gapbetween its upper end and a brass plug 42, by which the carrier is connected to the piston-rod 4.3. Said piston-rod pages through a hole in the cover of the magnet and is guided thereby, its limit of motion being determined by the end of'the projection 4% on said cover.

The piston-rod 43 is connected'with a piston said spring being 1 arranged 'in the recess formed in the lower part of the ,piston, against the top of Which one end of the spring bears, the other end of the spring being secured to the rod by a pin, so that.

upward movement .of'the core acts to compress sa1d spring and the spring in turn acts to lift the piston. In this construction movement of the core is dependent upon the strength of'the overload, but movement of the piston is constant, or substantially so. regardless of the strength of the overload. I

The plate bearing the movable circuitcontacts forms a part of or is attached to said piston, so that upward movement of the piston acts to move said circuit-contacts 1n a direction to engage the stationary circuit-contacts and close switch-controller.

the circuit 25 of the As it is necessary that naeesoo movement of the piston to cause the circuitcontacts to engage shall require a prolonged period of time, a retarding-device is provided to control the movement of the piston, and also to predetermine its speed of motion. The retardingc'levice shown" in Fig. 1 will now be described.

50 represents a'cup-shaped structure which forms the shell of a dash-pot, being supported by a bracket erected on the cover of the solenoid coil. The mouth of the dashpot is covered by a flexible diaphragm 51,

composed of flexible air-tight material, and

said diaphragm is connected at its edges to the cup in any air-tight manner. The center of thefieXible diaphragm is secured in an air-tight manner to a convex piston 52, having a curvature toconform to the face of .the cup 50.- The cup is shown as comparatively shallow since-a short movement only is required. In the top of thedashpot is a leak-valve of which 53 represents the valve-case having within-its "partition wall formed with a hole through it, and 5% represents a'needle-valve extended through the outer wal1 "o'f the case, and adapted to stem of said needle-valve is screw-threaded,

- so that it may be adjusted byturning it, and

' enter said hole more or less asmay be re; i quired for purposes; of adjustment. .The

it ha a finger-piece'55 by which it may be] adjusted manually. Saidneedle-valve has connected with it an arm 56, which is extended radially therefrom, and said arm '56, has connected with it a core-57, of asolenoid 58,1which is included in the transformer-circuit, so as to'be controlled by an .4

overload on the circuit 20, and upon: the

occurrence of an overload .saidso lenoid 58' will respond according to: the strength of according to the strength of'the overload. The leakage of air which i permitted by theneedle-valve is suiiicient-to insure a longer time-limit adjustment'of the dash-pot, by

varying the resistance, and, as will be 0bv served, such leakage of air may be regulated manually and also automatically. Y

In thetop of the dash-pot is also mounted a ball-valve 60, normallyclosing a passage leading from the interior of the dash-pot to the atmosphere, which permitso'f the entrance of air to the dash-pot easily and quickly, hen to normal.

Assuming thedevice of Figs. 1 and 2 isconnected in an electric-circuit substantially as shown, and an overload occurs on the circuit 20,-the core of the actuating solenoid is drawn up and-the spring-compressed and said spring in turn raises the movable elethe parts are beingrestored ment or operating-device of the switch-opcrating means, and movement. of said-ele- .ment is retarded by-the dash-pot, and such.

the overload, and will act to turn the needlevalve and thereb automatically adjust it to the strength of theoverload. It will be retarded movement is controlled or regulated by the leak-valve; and it will be noted that the pperating-means for the switch is actuated by means operated by the overload, and its movement is regulated or controlled by means operated by the overload, that is to say, the prolonged period of timeconsumedby it in operating is varied according observed that the arm 56 is drawn down variable'distances according to the strength of the overload and the leak valve correspondingly opened, thereby to correspondingly re-.

dnce the period of time consumed by the switch-operating means in operating, but on.-

all overload-s of high current ,valuessaid arm 56 is drawn down its maximum distance,

and the leak-valve correspondingly opened itsniaiiiinuin distance,.and the prolonged period of time-is correspondingly reduced, but the same for all overloads of high curvalues. Thus the device embodies the inverse tlin llllllt feature on overloads up to i i-predetermined current value, and on Us of all higher current values itoverl embodies the definite feature. 1

Referring to F 1g. 3, a solenoid 70, of ordiner construction is emplo ed as the actuator for theswitch-operat-ing means, which is connected in the transformer-circuit, and

its core is connected directly with the mov-i able operating-device oi the switch-controL ler, the spring being omitted, and in th s construction the operating-device is moved positively by the core, so that its movement 1 is dependent upon the overload and variable according to the strength thereof, instead I eration of the switch and not an apparatus i with high power,

of being constant regardless'of the strength thereof, as shown by the device of Fig. The. structure shown in the various figures are merely for the purpose of -illustrating different embodiments of my invention, and

it is obvious that changes may be madetherein withoutdeparting from, the spirit and scope of the invention.- Y

in this specification the word retardingdevice is used in a literal sense, to indicate a device which actually retards the opwhich merely operates slowly and is a re-- tarding-device only in the sense that operating a contact with weal; power constitutes retarding, as compared with operating it '1 1. A time-limit controlling-device tor 'elec tric switches including in combination opcrating-means for the switch, aretardingdevice for said operating-means, means toactuate said operating-meanswitha constant force, and means responsive to an overload current, to variably adjust the retarding efitector said retarding -'device and conse- 1 quently the speed of operation ct theoperat- ,ingneans for the switch according to the I eratingmeans strength of the overload, substantially as described.

A time-limit controlling-device for electric switches including in combination operating-means for the switch, a retarding-device for said operating-means, means eperated by an overload current for supplymg power to said operating means, said op,- rating means acting with'substantially constant force to operate saidswitch, and means responsive to an overload current to variably adjustthe retarding eiiect of said retarding-dcvice and consequently the speed of. operation of the operating-means for the switch according to the strength of the over- 'load,-substantially as described.

3. A selective time-limit controlling-device for electric-switches including in combination a switch controller, an operatingdevice tor said switch-controller, a'retard ing-device for said operating-device, means controlled by the overload current and adapted to actuate the operating device .ivith a substantially constant force, and means responsive to the overload current to *regulatethespeed of motion of lug-device, substantially as described. 5

, a the retardi. A time-limit controlling-device for x electricswitches, comprisinga switch hav mg a' movable element, a solenoid operating at a predetermined. overload to compress a spring, a'movable contactmeniber for the switch and adapted-to be operated by said compressed spring, a bellows device adapt-- ed to retard the speed oifoperat-ion of said movableswitch member, having an escape opening adapted to be varied insize according to the strength of the overload, substantially as described.

5. A selective time-limit controlling dea vice for electric-switches ncluding a solenoid'responsive to an overload current, op-

for the switch actuated thereby (a fluid-controller timing-device to regulate the speed of motion, a regulating valve for said timing-device, and means controlled by the overload current to automatically open said valve by an amount varying according to the strength of the overload,

stantially as described.

6. A selective time-limit controll ng-device for electric-switches comprising a controlling-magnet adapted to compress a spring in response to an overload current,

operating means for the switch actuated by the expansion of such compressed spring; a timingedeviceto regulate the speed of mo- 'tionof' said operating-means having a con-- the orifice in response to an overload up to a predetermined current value,

- means to actuate at a constant speed, and means responsive to an overload current to variably ad ust trolling-valve,and means responsive to an overload you" ntfto variably control the movement said valve up to a predetermined current value, and to open said valve full on overloads of higher'current values, su stantially as described.

7. In a time-limit device, the combina tion of a device which is movable in response to an overload current, a member having an orifice, afluid whichsuch movement tends to force through said orifice, and means for variably adjusting the size of and manual means to adjust the minimum opening of said valve whereby the speed of operation of the device may be set for a predetermined series of times, varying according to the strength of the overload up to a predetermined current value, and will be definite at all higher current values, substantially as described.

8. A selective time-limit controlling-device for electric-switches including in combination operating-means for the switch, means to actuate said operating-means, a retarding-device connected with the operating-means to retard its operation, and means responsive to an overload. current to variably adjust the speed of motionof said retarding-deviceaccording to the strength of the overload, up to a predetermined currentvalue, and to definitely adjust its speed of motion on overloads of higher current values, substantially as described.

9, A selective time-limit controlling-device for electric-switches including in combination operating-means for the switch,.

means to actuate said operating-means, a retarding-device connected with the operating means to retard its operation, and means responsive to an overload current to variably adjust the speed of motion of said retarding-device according to the strength of the overload, up to a predetermined cur? rent value, of motion on overloads of higher current values, said retarding-device having means permitting of its quick recovery up'on cessation of the overload, substantially as described.

10. A selective time-limit controlling-device for electric-switches including in combina'tion operating-means for the switch, a retarding-device for said operating-means, said operating-means the speed of motion of said retarding-device according to the strength of the overload, up to a predetermined currentvalue, and to definitely adjust its speed of motion on overloads of higher current values, substantially as described.

11. A selective time-limit controlling deoverload current to vary of said retarding-device according 'to the,

4 higher current values,

2 higher current values,

and to definitely adjust its speed vice for electric-switches includingin combination operating-means for the switch,

means controlled by an overload current to actuate said operating-means, a retardlng- 1 device to retard movement of said operating:

means, and means also controlled by the the speed of motion strength of the overload, up to a predetermined current value, and to definitely adjust its speed of motion on overloads of substantially as described. 1

12. A selective time-limit controlling-device for electric-switches including in combination operating-means means controlled by an'overload current to actuate said operating-means at a constant speed, a retarding-device for said operatingmeans, and means responsive to the overload current to varlably adjust the speed of motion of said retarding-device according to the strength of the overload, up to a predetermined current value, and to definitely adjust its speed of motion on overloads of substantially as described. Y

13. A selective time-limit controlling-dc vice for electric-switchesincluding in combination operating-means for the switch, means operated by an overload current to actuate said operating-means, a retardingdevice to control the movement of said operating-means, and means controlled by the overload current to increase the speed of motion of said retarding-device according to the strength of-the overload, thereby to 'fl-"Q- duce the time required for the operatingmeans to operate the switch according to the strength of the overload, up to an overload of a predetermined current substantially for the switch,

I value, and to definitely adjust its speed of motion on over vice for electric-switches including in com-.

bination acontrolling-magnet responsive to an overload current, operating-means for the switch actuated thereby, a retarding-device for said operating-means, and means responsive to an overload current to regulate the speed of motion of said retarding-device, up to a predetermined current value, and to definitely adjust its speed of motion on overloads of higher current values, substantially as described.

15. A selective time-limit controlling-device for electric-switches including a controlling-magnet responsive to an overload current, operating-means for the switch actuated thereby, a retarding-device for said operating-means, and means responsive to an overload current to reduce the resistance of said retarding-device according to the strength of the overload, up t9 a predetermined current value, and to definitely reduce the resistance of said retarding-device on overloads of higher current value, substantially as described.

16. A selective time-limit controlling-desaid timing-device up 'to a predeterminedcurrent value, and for definitely adjusting saidtiming-device on overloads of higher current values, substantially as described.

l7. A time limit controlling-device for electric switches, including" in combination operating-means for the switch, a .solenoid responsive to an overload current to actuate said operating-means, ,an air bellows arranged to be compressed by the closing movement of said operating means for the switch, a valve for said bellows, and a solenoid responsive to an overload current adapted to variably open thevalve of said bellows in accordance with the strength .of the overload, substantially as described.

18. A time-limit controlling-device for electric switches, including, in combination operating-means for the switch, a solenoid responsive to an overload current to actuate said operating-means, an air bellows arranged to be compressed by the closing movement of said operating means for the switch, a valve for said bellows, and a solenoid responsive to an overload current adapted to variably open the valve of said bellows in accordance with the strength of the overload, and manual'means to adjust the minimum opening of said valve whereby the speed of operation of the device may be setfor a predetermined series of times, varying according to the strength of the overload u to a predetermined current value, and will be definite at all higher current values, substantially as described.

Intestimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

Witnesses B. J. Norris, H. B.;DAvIs. 

